DD301289A7 - Class 2 ceramic dielectrics according to IEC (solution 2) - Google Patents

Abstract

The invention relates to dielectrics for capacitors, in particular for multilayer and disk capacitors, and active substances for printed capacitors. According to the invention, ceramic materials of technically pure raw materials based on the separately preformed components Ba ind m TiO 3 (Pb ind x Sr ind 1-x) ind n ((Mg in 1/3 Nb in 2/3) ind y Ti ind 1-y) O ind 3 (Pb ind z A ind 1-z) ind l (v ind 1 B ind 1 ... v ind i B ind i) Oind 3 and (Pb ind t D ind 1-t) ind p (Ti ind q Zr ind s (u ind 1 C ind 1 ... u ind j C ind j) ind 1-qs) O ind 3 and glass additions of the oxides PbO, ZnO, B ind 2 O ind 3, SiO 2, Al 2 O 3 and Bi 2 O 3 which are added at least partially fritted, at different sintering temperatures and Curie points of the preformed components, taking into account the elements usable for A, B, C and D, and in the description of the invention by l, m, n, p, q, s, t, u, v, x, y and z specified molar proportions and adhering to the stated mass fractions of these 5 components and preservation of the multiphase in the sintered material suitable dielectrics Class 2 R 1 according to IEC with dielectric constant epsilon ind r> = 3 000.

Description

0.85 mass parts PbO 0.07 to 0.06 mass parts B ₂ O ₃ 0.04 to 0.06 mass parts ZnO 0.01 mass parts Al ₂ O ₃ 0.01 mass parts SiO ₂

and a remainder of max. 0.03 mass fraction of impurities and fluorides.

6. Ceramic dielectrics according to claim 1, _{2, 3} or 4, characterized in that the glass additive preferably consists of a fritted solder glass and further of the oxides mentioned under claim 1, in particular of Bi ₂ O ₃ .

Field of application of the invention

The invention relates to the field of electrical engineering / electronics and relates to ceramic dielectrics for capacitors, in particular for multilayer and Scheibenkondansatoren, and active substances for printed capacitors.

Characteristic of the known state of the art Miniaturization of capacitors and improvement of material economy and labor productivity in manufacturing

These capacitors experience an increase in the dielectric constant ε, the effective dielectric while maintaining the lowest possible temperature dependence thereof, z. B. of max. ± 15% in the temperature range from -55 ⁰ C to

+ 125 ⁰ C for class 2R1 according to IEC and X7R according to EIA standard. .

It is generally known that the increase of the ε, by the use of ferroelectric ^ materials such. B. LaTiO ₃

or mixed crystals, is reached, with increasing ε, increasing dependencies of the same must be taken of the temperature, and that surcharges to lower the sintering temperature T ₁ , in the usual ceramic

Multilayer capacitors especially for lowering the proportions of high-melting expensive precious metals Pd, Pt or Au in the

can lead between the dielectrically active layers lying electrode layers, the ε, lower.

If the temperature characteristic of class 2R1 is maintained and the sintering temperature T is below 1140 ^° C., the solution becomes weaker DD-PS 258915 a technologically manageable and reproducible solution. With their compositions on the basis

of BaTiO ₃ and mixtures of bismuth layer compounds and other additives, however, only ε, values are reached around 2000.

Other known solutions, such as DD-PS 140871, DE-OS 2923981, US-PS 3619220, DE-AS 1640168 and US-PS 3619744

reach the state of the solution according to DD-PS 258915 not by giving either lower ε, values and / or the

Class 2R1 is not enough. Also known is a solution consisting of 2 components of BaTiO ₃ , of which at least 50% of the used Mass fraction must be in the particle size range of 0.7 to 3.0 mm, and a complex Bleiperowskit according to EP 257653. However, the dielectrics corresponding to this solution, which satisfy class 2R1, only achieve ε, values of max. 2920 at Sintering temperatures T ₁ , which are not lower than 1200 ⁰ C. Another solution, according to EP 205137, results in compliance with the temperature characteristics of class 2R1 in the best case

ε, values of 3 205. In this case, one with Nb] Oj or Ta ₂ O ₆ and Sm ₂ O ₃ or other oxides of the SE elements of the

Ordnungszahlen 57 to 62 added BaTiO ₃ and further separately supplied dopants of a mixture of MnO ₂ and NiO

used. The main disadvantage of this solution, which requires a sintering temperature T, of 1230 ° C, and all solutions

EP 205137 A2 are the high demands on the main component BaTiO ₃ . The high ε, values are achieved only when using a high-purity, very fine BaTiO ₃ : The solution requires particle sizes

of S1 pm and total impurities of SiO ₂ , Al ₂ O ₃ and Fe ₂ O ₃ of less than 0.2 mass% in%. In the usual

industrial _BaTiO3 -Herste !! 'ing this can analytically pure only when using more expensive raw materials and special, more expensive to achieve grinding media. Furthermore, these materials are very sensitive to sintering. Even with minor deviations from the optimum sintering temperature, the temperature characteristic of class X7R is no longer complied with. Moreover, this occurs on Riesonkorn growth, which excludes the use in ceramic Vielschlchtkondensatoren in which already sintered effective dielectric layers are realized with thicknesses from 25μιη today.

Object of the invention

The object of the invention is to find material compositions which, when using industrially produced BaTiOj, enable reproducible production and advantageous technical data in the case of ceramic dielectrics of the class according to IEC compared with the prior art.

Explanation of the essence of the invention

The invention has for its object to find compositions which, when using BaTiO ₃ with a particle size d _M 23,5μηι and a purity of 0.98 parts by weight and other at least technically pure raw materials, including rare earths or deron mixtures, at sintering temperatures T ₁ S 1200 ⁰ C and a possible sintering interval of at least 3OK ceramic dielectrics with dielectric constant ε, ä 3000 class 2R1 according to IEC revealed, which are also suitable for use in ceramic multilayer capacitors with thicknesses of the sintered, dielectrically active layers> 25pm. ·

According to the invention this object is achieved by compositions of four preformed components K1 to K4 and an addition of a low-melting point glass G:

K 1 = Ba _n JiO ₃

or Ba _1n TiO ₃ with dopants, wherein m = 0.97 ... is 1.00, K 2 = (Pb _x Sr, _, U (MgU ₃ Nb ₂ _ Z ₃₎ Ji _{1 V]} O ₃

with χ = 0.75 ... 0.98 y = 0.70 ... 0.9B

and η = 0.98 ... 1.06, the dichtsintert at a sintering temperature between 1150 ° C to 1250 ⁰ C and at 25 ° C a dielectric constant ε, has> 4000,

K3 = (Pb ₁ A ₁ -.Wv ₁ B ₁ ... ViBi] O ₃ ,

Of which at least 0.6, but not more than 0.95 molar fractions of Pb ^ FeIz ₂ NbIz ₂ IO ₃ with A ^ Sr, Ba, Ca

B, ... B, & Mg ²⁺ , Ni ²⁺ , Zn ²⁺ , Fe ²⁺ , Co ²⁺ , Mn ²⁺ , Fe ³⁺ , Co ³⁺ , Mn ³⁺ , Sc ³⁺ . Ti ⁴⁺ , Zr ⁴⁺ , Sn ⁴⁺ , Hf ⁴⁺ , Nb ⁶⁺ , Ta ⁶⁺ , Sb ⁵⁺ , W ⁸⁺ , where Vi ... V | dia corresponding quantities of B | ... B | and W ₁ ... W | the valences of B ₁ ... Bi mean that

i i

the Moltersky conditions for perovskites £ vi = 1 and £ w, V | = 4,

1

ζ = 0.80 ... 1.0 and i = 0.98 ... 1.06, the sintered sintered at a sintering temperature between 93O ⁰ C and 1060 ⁰ C and thereby in the temperature range from -2O ⁰ C to + 6O ⁰ C has in a maximum a dielectric constant ε,> 8000, and

K 4 = (Pb ₁ D ₁ -,) _p | Ti _q Zr, (u, C, ... UjCj) ₁ _ "_,] O ₃

with DA Sr, Ba, Ca, SE or Didym, C ₁ ... CjS Selection as below B ₁ ... B /, where U ₁ ... Uj the corresponding mole fractions of C | ... Cj and W ₁ .. .Wj mean the valences of C ₁ ... Cj, the

j i

must satisfy the Molensky conditions for Poroskiteq + s + £ u _f = 1 and 4 (q + s) + EwjUj = 4,

1

with q = 0.40 ... 0.60, s = 0.30.

and q + s> 0.80,

t = 0.80. t = 0.93. and ρ = 0.98.

.0,55

, 1.00 for D = Sr, Ba, Ca or .1,0OfUrDASE or Didym .1,06,

which at a sintering temperature 115O ⁰ C dense sintered, the dielectric constant ε, at 25 ⁰ C> 2300, a maximum at> 15O ⁰ C weir; and slowly decreases after negative temperatures, 'jnd G is low-melting glass with a hemisphere point up to max. 700 ° C, which consists of at least three of the six oxides PbO, ZnO, B ₂ O ₃ , SiO ₂ , Al ₂ O ₃ and Bi ₂ O ₃ . Both glass fritted glasses and mixtures of these with further of the stated oxides are considered glass additives G.

The mass fractions of the 4 preformed and comminuted components K1 to K4 and the glass additive G in the desired material composition are:

K1 = 0.30 ... 0.67 mass & parts K2 = 0.10 ... 0.55 mass fraction K3 = 0.005 ... 0.10 parts by weight

K4 = 0.05 ... 0.25 parts by mass and G = 0.01 ... 0.03 parts by mass,

4 4

where Σ Κ = 1.0 and the indication of G is referred to as supplement to £ K and wherein in the case of a mixture of 1 1

fritted glass with oxide of oxide content max. 50%.

Depending on the composition, the dense sintering of the body formed from this mixture in a known manner at a sintering temperature T ₁ in the range of 1100 ° C and 1200 ⁰ C take place.

Compliance with all other requirements of a capacitor material class 2R1 according to IEC, the dielectric constant ε, at 25 ° C reaches values from 3000 to 4000, with their change in the operating temperature range of -55 ⁰ C to + 125 ⁰ C ± 15% does not exceed and thus corresponds to the class.

Exceeding or undershooting the stated limits for the mass fractions of the four components and the glass additive in the total offset of the material have the following effects:

In the case of the component K1, they lead to no longer flat temperature profile of the E ₁ , when exceeded, the required sintering temperature rises well above 1200 ⁰ C.

If the proportion of component K2 is exceeded, the ε, which is still high at low temperatures, drops too steeply after higher temperatures; if the proportion falls below this level, negative temperatures lead to an ε, -fall of more than 15%. If the claimed component of component K3 is exceeded, the dielectric losses rise to higher temperatures, the insulation resistance drops below values of 10 ¹⁰ O. Underruns complicate the density sintering. Increasing the proportion of the component K4, so the allowable maximum for the class 2R1 ε, -Slope of 15% at -55 ° C and can not be complied with, at the upper limit of the temperature range at +125 ⁰ C, which allowed ε is , Waste not exhausted. Accordingly, if the proportion for K4 falls below +125 ⁰ C, it can lead to a strong ε, -Abfall.

By falling below the limits for the glass content increase the required sintering temperatures T ₁ , and / or lower densities of the ceramic can be achieved. If the proportion of the glass is exceeded, the ε ,, decreases and the desired temperature dependence is not maintained. In particular, for the production of thin films, such. B. for multilayer capacitors, the claimed glass content allows even at low sintering temperatures to achieve a high density, faster shrinkage, low pore space and thus increase the dielectric strength and lowest moisture sensitivity of the capacitors. The possible lower sintering temperatures are contrary to the preservation of the multiphase of the total material and thus the low temperature dependence of the ε, as well as unnecessary special measures to regulate the PbO household during sintering.

Ausführungsbelsplele The invention is described below with reference to five exemplary embodiments in the form of two tables and the explanation of itself

known, in principle in all embodiments of the same process steps for the preparation of the individual components K1 to K4, the glass additive G and the total material on the basis of the composition according to Embodiment 1 explained in more detail.

Table 1 gives the composition and the applied sintering regime, characterized by sintering temperature T, and Holding time, on. Table 2 shows the obtained technical characteristics of the selected types of specimens. The starting point of the synthesis is the preparation of the four components and the glass additive. Component K1: BaTiOj Component K1 is prepared in known manner from equal molar proportions BaCO ₃ and TiO ₂ in a two-hour Solid-state reaction at 1200 ⁰ C formed. Subsequently, fine grinding takes place in drum or vibratory mills. A TiO ₂ excess of up to 0.03 mole fractions is not critical. Component K2: First, is represented by a solid state reaction at 1100 ⁰ C MgNb ₂ O _{6 6} made of MgCO ₃ and Nb ₂ O. An excess of 0.04 molar proportions of Mg in the offset is not only uncritical, but even favorable. The preformed MgNb ₂ Oe is added according to the proportions by moles of PbO or Pb ₃ O ₄ given by the formula SrCO ₃ and TiO _{2 are} added and this mixture is annealed at 1100 ° C / 2h. This product is then finely ground to a particle size d ₆₀ S 5 pm. There is an excess of up to 0.06 Substance quantities PbO or Pb ₃ O ₄ permissible. The sintered at 1175 ° C / 2h component K2 has as a single component an ε,> 5000 at 25 ⁰ C. The ε, maximum at

is about 50 ° C, has values of> 8000. The structure is perovskite with low levels of pyrochlore residue.

Higher annealing of the component K2 is possible, but not advantageous, since the subsequent comminution thereby

becomes more difficult and the required sintering temperature T _{2 of} the total material increases.

Component K3: Pbo.oaSro.oaKFevjNbwjlo.eefFeMWt / slo.oelNimNbvaio.osSno.oalOa The preparation is carried out by direct synthesis from the raw materials Pb ₃ O ₄ or PbO, SrCO ₃ , Fe ₂ O ₃ , Nb ₂ O ₆ , WO ₃ , NiO and SnO ₂ , which are mixed according to the molar proportions given by the formula and calcined at 800 "C / 2 h.

The subsequent fine grinding took place for 6 hours in an agate powdered iron. A shortening of the grinding time is possible

(dg, at least 5 5μηι). An excess of up to 0.06 molar amounts of PbO or Pb ₃ O ₄ is not critical.

This material, which is used here as component K3, has the following values on disk-shaped test specimens which, at 1020 "C / 2 h in-situ, have the following values:

E, at 25 ⁰ C "17000 E, -Maximumbei29 ° C.

Similar values are achieved when two subcomponents, one from the raw materials Pb ₃ O ₄ or PbO, Nb ₂ O ₆ and WO ₃ at 700 ° C / 2 h and the second from the remaining raw materials at 1000 ° C / 2 h, are preformed separately and the further treatment of the component K3 takes place with the proportions given by the formula.

Component K <: Pb [Zro, 4eTio, ₄ e (Nii / ₃ Sb _{2, 3) 0i0} 8L0 ₃

The preparation is carried out by direct synthesis from the raw materials Pb ₃ O ₄ or PbO, ZrO ₂ , TiO ₂ , NiO and Sb ₂ O ₃ by these are mixed according to the given by the formula molar proportions and the mixture of a Fostkörperreaktion at 850 ° C bh 900th ° C with 2 h holding time is subjected. It is followed by a fine comminution to a particle size of dge s 5μπΊ, which happened in this case in a 3-hour treatment in a Agatpulverisette.

The densely sintered at 1280 ° C / 2 h component K4 has as a single component at 25 ⁰ C an ε, of 2 500. The ε, maximum is about 28O ⁰ C.

Glass additive G:

0.85 mass parts PbO 0.07 mass parts B ₂ O ₃ 0.06 mass parts ZnO 0.01 mass parts Al ₂ O ₃ and 0.01 mass parts SiO ₂

are mixed, the mixture melted in a corundum crucible at 1000 ° C, stirred several times and kept liquid for one hour. Thereafter, the melt is quenched by pouring into cold water, the glass phase is separated from the water, dried, pre-crushed and ground in an agate powder so that the powder has a BET specific surface area of at least 2.5 mVg.

Belongs, as in the embodiment 5 with Bi ₂ O ₃ , nor a ungrittetes oxide to the glass additive, wherein the same oxide could already have been part de: frit, then this oxide can either be mixed in the fritted part of the additive G or separated be added to the offset of the total material.

To produce the embodiments according to the invention of the overall material, the components K1 to K4 prepared in this way or in the same way are mixed with the glass additive G in the proportions given in Table 1 and advantageously annealed again at 1000 to 1050 ° C./1 h and finely ground. This repeated homogenization and fine grinding, which serves for improved homogenization, can also be omitted.

In any case, the powdery, inventive material of the product-specific known shaping and possibly other required process steps, as for multilayer capacitors, for. metallization and the like, and then sintered.

Table 1 Composition and mass fractions de. components

Out- Component 1 Component 2 Component 3 Material- Component 4 G τ. ro leadership men-Jen Holding time (h) rungs- anteiie Ex. in%

BaTiO ₃

Pb [Fe _1/2 Nb _1/2 ] O ₃

Pb [F _{e2 / 3} W _1/3 ] O ₃

Pb [Ni ₁ Z ₃ Nb _2n ] O ₃

SrSnO ₃

+ 1Ma .-% PbO

86 6 5 3

Pb [Zr _0-48 Ti _0-4

BaTiO ₃ 45%

(Pb _0-88 Sr _0-12 ) I (Mg ₁ Z ₃ Nb ₂ Z ₃ ) O _-8 Ti _0-2 ] O ₃

45%

Pb [Fe ₁ Z ₂ Nb ₁ Z ₂ ] O ₃ 86 Pb [Zr _0-46 Ti _0-46 Pb [Fe ₂ Z ₃ W _1n ] O ₃ 6 (Ni _1n Sb _2n I _0- O Pb [Ni _1n Nb ₂ Z ₃ ] O ₃ 5 SrSnO ₃ 3 + 1Ma .-% Pb0 3% 7%

Lotglas system

- PbO

- ZnO

- SiO ₂ -B ₂ O ₃

- Al ₂ O ₃

solder glass

+ 1.5%

Alb 40% 40% 40% 40% 1% 1% 60 30 10 19% 19% + 1.5% + 1.5% 1200/1 A2 BaTiO ₃ 55% (Pb _0-90 Sr _0-10 ) I (Mg ₁ Z ₃ Nb _2n ) O- ₉ Ti (J ₁₁ ] O ₃ 25% Pb [Fe ₁ Z ₂ Nb ₁₇₂ ] O ₃ Pb [Fe _2n W ₁ Z ₃ ] O ₃ Pb [Zn _1n Nb ₂ Z ₃ ] O ₃ 10% wieA2 Pb [Zr _0-40 Ti _0-50 (Mg ₁ Z ₃ Nb _2n J _0-10 ] O ₃ 10% Solder glass + 1.5% 1160/2 A3 like A 2 like A 2 like A 2 like A 2 wieA2 1180/2

like A 2

as a

like A 2

wieA2

like A 2

+ 1.0% solder glass + 2.0% Bi ₂ O ₃ , unfilled

Table 2

Ausführungsbeisp.

design

1 measuring frequency: 1 kHz.

2 measured at 25 ° C.

3 based on 25 ⁰ C.

ε,

tanö "·" HO " ³ )

Insulation resistance R ,. ²¹ (Ω)

Δε max. deviation in%³¹ In the range of

-65 ° Cbi8 +25 ⁰ CbIe

+25 ⁰ C · +125 ⁰ C

A1a disc 3200 16> 10 11 _{+ 2} - 9 + 3 - 6 A1b disc 3300 16> 10 ¹¹ -11 + 2 - 7 A2 disc 3200 16> 10 ¹¹ +8 + 2 -12 A3 disc 3 500 18> 10 11 _12 + 5 - 8 A4 disc 3300 16> 10 ¹¹ +8 + 2 -12 A5 disc 3100 16> 5 · 10 "+ 2 - 8 + 5 -10

Claims (5)

1. Class 2 ceramic dielectrics according to IEC on the basis of five different components essentially known in their basic composition, barium titanate, three complex lead pervalskites and added glass, characterized in that at least two different sintering temperatures of the separately preformed components K1 to K4, at least two different Curie temperatures have unci that the components are in the range of the following composition: K 1 = Ba _m TiO ₃ with m = 0.97 to 1.00, whereby the barium antidote may also contain up to 3 parts by weight i: i% of the usual dopants, K 2 = (Pb _x Sr _1. ,, U (Mg ₁ Z ₃ Nb ₂ Z ₃ ) VTi ₁ - _V ] O ₃ with χ = 0.75 ... 0.98 y = 0.70 ... 0.95 and η = 0.98 ... 1.06, of which at least 0.60, but max. 0.95 mole fractions PbZ [Fe ₁ ZaNb ₁ Z ₂ ) O ₃ , with A = Sr, Ca, Ba, B ₁ ... B ₁ δ Mg ²⁺ , Ni ²⁺ , Zn ²⁺ , Fe ²⁺ , Co ²⁺ , Mn ²⁺ , Fe ³⁺ , Co ³⁺ , Mn ³⁺ , Sc ³⁺ , Ti ^{4 +} , Zr ⁴⁺ , Sn ⁴⁺ , Hf ⁴⁺ , Nb ⁵⁺ , Ta ⁵⁺ , Sb ⁵⁺ , W ⁶⁺ , ii where Y ₁ ^ i = 1 and Hw ₁ Vj = 4, if V ₁ ... V _{1 are} the corresponding ones 1 1 Substance quantities of B ₁ ... Bj and W ₁ ... Wj denote the respective valences of these B ₁ ... Bj, ζ = 0.80 ... 1.0 and / = 0.98 ... 1.06, K 4 = (Pb ₁ D ₁ _, Jp [TiCZr ₅ (U ₁ C ₁ ... UjCj) ₁ _ _q _ _S ] O ₃ with Sr, Ba, Ca, SE or Didym, C ₁ ... C j a Mg ²⁺ , Ni ²⁺ , Zn ²⁺ , Fe ²⁺ , Co ²⁺ , Mn ²⁺ , Fe ³⁺ , Co ^{3 +} , Mn ³⁺ , Sc ³⁺ , Ti ⁴⁺ , Zr ⁴⁺ , Sn ⁴⁺ , Hf ⁴⁺ , Nb ⁵⁺ , Ta ⁵⁺ , Sb ⁵⁺ , W ⁶⁺ , ] Tv where q fs + £ uj = 1 and 4 (q + s) + £ ^w j ^u i = 4 if U ₁ ... Uj the 1 corresponding molar quantities of C ₁ ... Cj and W ₁ ... Wj denote the respective valences of these C ₁ ... Cj, q = 0,40 ... 0,60 S = 0,30 ... 0,55 , where q + s> 0.80, t = 0.80 ... 1.00 for D £ Sr, Ca, Ba or t = 0.93 ... 1.0OfUrD ^ SEOdOrDIdVm and ρ = 0.98 ... 1.06, G is a low-melting, mostly partially fritted glass addition of at least three of the six oxides PbO or Pb ₃ O ₄ , ZnO, B ₂ O ₃ , SiO ₂ , AUO ₃ and Bi ₂ O ₃ with a hemispherical point below 700 ⁰ C, that they in the mass fractions K1 = 0.30 ... 0.67 K2 = 0.10 ... 0.55 K3 = 0.005. ..0.10 K4 = 0.05 ... 0.25 and G = 0.01 ... 0.03 4 are included in the offset of the respective ceramic dielectric, where £ K = 1.0 and the proportions of G are related to this sum, and that the sintered material is multi-phase according to the components. 2. Ceramic dielectrics according to claim 1, characterized in that the component K2 preferably at 25 ° C has a dielectric constant ε _Γ > 4000 and between 115O ⁰ C and 1250 ⁰ C dense sintered. 3. Ceramic dielectrics according to claim 1 or 2, characterized in that the component K3 preferably between 930 ⁰ C and 1060 ⁰ C dense sintered and between -2O ⁰ C and + 6O ⁰ C has an ε, maximum> 8000. 4. Ceramic dielectrics according to claim 1,2 or 3, characterized in that the component K4 preferably at a sintering temperature> 115O ⁰ C dense sintered, at 25 ⁰ C has a ε _Γ > 2300 and at> 150 ⁰ C an ε, -Maximum having. 5. Ceramic dielectrics according to claim 1, 2, 3 or 4, characterized in that the glass additive preferably comprises fritted solder glass made from an oxide mixture of